1. Field of the Invention
This invention relates generally to OPO systems, and more particularly to OPO systems where the OPO is internal with the pump source.
1. Description of the Related Art
A number of sensing applications are moving towards the use of eyesafe near infrared laser systems (14xx nm-16xx nm (and possibly others)) in order to make the devices safer to use for general sensing applications by non-typical laser users under safely controlled laboratory conditions. To this, Quantel has designed a laser/OPO (optical parametric oscillator) system that operates across this tuning range, is tunable or can be operated at a fixed wavelength, is highly efficient, and can be pumped with a variety of sources. The primary application for the system described here is for LIBS (Laser Induced Breakdown Spectroscopy), but the described device could be used for a variety of other sensing applications.
The normal implementation of an eyesafe system is either through the use of direct generation of the light (via various exotic rare-earth doped crystalline materials), or through secondary generation of the light (via harmonic generation, sum or difference frequency mixing, etc. or via optical parametric oscillation (OPO) in nonlinear optical (NLO) materials).
Each of these processes has advantages and disadvantages. The use of direct generation via rare earth doped crystalline materials (flashlamp pumped, diode pumped, or other) is an effective way to generate various wavelength emissions for use in sensing. However, these materials are difficult to grow, often have poor efficiency, are susceptible to optical feedback, and are generally fixed in output wavelength. Secondary generation via harmonic or mixing processes, are inefficient, generally bulky, and complex to operate. Secondary generation via optical parametric oscillation, OPO pumped by a laser source, can be easy to implement, rugged, and easy to build but generally suffer from poor energy stability, short pulsewidths, and beam quality problems (poor uniformity, poor divergence, etc.).